In recent years, many three-dimensional (3D) movies are appearing, and thus many techniques related to 3D image display apparatuses are being studied. Since the 3D image display apparatuses display 3D images based on binocular parallax, 3D image display apparatuses which are being currently commercialized use binocular parallax of two eyes of a viewer. As a left-eye image and a right-eye image having different viewpoints are provided to the left and right eyes of a viewer, the viewer may perceive a stereoscopic effect. Such 3D image display apparatuses may include glasses type 3D image display apparatuses for which special glasses are necessary and non-glasses type 3D image display apparatuses for which glasses are not necessary.
However, when the viewer watches a 3D image displayed in a binocular parallax fashion, the viewer's eyes feel very tired, and 3D image display apparatuses configured to provide only two viewpoints, i.e., a left-eye image and a right-eye image, do not reflect a viewpoint change according to the movement of the viewer. As such, there is a limitation in providing a natural stereoscopic effect to the viewer.
In order to display more natural stereoscopic images, holographic display apparatuses are being studied. Light may be considered to be waves having amplitude information and phase information. A holography technique controls a phase and an amplitude of light to display an image. Accordingly, in the holographic display apparatuses, a device capable of controlling an amplitude (intensity) and a phase of light is necessary.